Though most Americans who lack insurance — 63 percent — say they’ll obtain insurance by January, a substantial 28 percent said they wouldn’t enroll and instead would pay a fine, according to new Gallup numbers.

The reluctance to buy insurance in the exchanges is higher among Republicans: 45 percent of uninsured Republicans plan to pay the fine, compared with 31 percent of independents and 15 percent of Democrats.

Under PPACA, nearly all Americans have to buy insurance by the beginning of the year or pay a fine. In 2014, the penalty is 1 percent of the person’s income or $95, whichever is higher.

Among uninsured young adults — a key demographic needed to make the economics work — 26 percent of say they’re more likely to pay the fine, compared with 30 percent of those 30 and older.

Additionally, Gallup said awareness of PPACA isn’t the biggest hurdle anymore. The pollsters said that 81 percent of uninsured Americans claim to be aware of the requirement to have insurance or pay a fine.

“The biggest challenge to achieving universal coverage, however, may not be in making Americans aware of the requirement or in getting younger uninsured Americans to sign up,” Gallup concluded. “Rather, it may be getting those likely to oppose the law, namely Republicans, to overcome their ideological opposition to the law and sign up for insurance.”

Gallup researchers said its latest poll could have big implications for PPACA goals.

“More than a quarter of people without health insurance say they are willing to pay a fine rather than enroll in a health plan under the Patient Protection and Affordable Care Act,” they said.